1. Field of the Invention
The present invention relates to memory management, and more particularly, to a memory management apparatus and method for accessing digital versatile disc data.
2. Description of the Prior Art
In recent years, data storage capacity of storage media has increased considerably. Compared with other storage media, optical discs have the advantages of low price, small size, low error rate, durability, and high-density storage. Optical discs are commonly divided into two types: compact discs (CDs) and digital versatile discs (DVDs), wherein the digital versatile discs have the higher storage capacity between the two.
Digital versatile disc data is saved on the disc in a unit called a “sector”. Each sector has 13 data lines, and each data line has 182 bytes. Out of the 182 bytes, the first 172 bytes are data to be saved, and the latter 10 bytes contain conventional error correction code (ECC). Furthermore, every 16 sectors constitute a “block”; so each block has a data storage capacity of 32 k bytes in total.
When an optical disc system reads data on the digital versatile disc, the data should first be copied into a memory device of the optical disc system in sectors. Because the sector size of the digital versatile disc data is different from the size of the storage unit in the conventional memory device (for example, 128 bytes per storage unit), it becomes inevitable, when copying data on the digital versatile disc into the memory device, to either divide up the data of a sector in order to fully utilize all of the storage space in the memory device; or otherwise, to leave part of the storage space unused in the memory device in order to store only one complete sector of the digital versatile disc data into one storage unit at a time. The above-mentioned two approaches have their respective advantages and disadvantages. The first approach can save the data storage space, but if the digital versatile disc data is to be accessed, it requires more complicated computing processes to obtain a physical data address. Adopting this approach not only increases workload of the system programmer in the developing phase, it also requires that during operation, each and every data processing module in the optical disc system repeats said computing processes to obtain the address where the digital versatile disc data is stored. The second approach avoids said computing processes, but in turn decreases the utilization rate of the memory device.